1. Field of the Invention
This invention relates to a method for the production of a material for a composite article and more particularly to a fibrous material for a composite article which comprises a matrix of thermoplastic resin fibers and reinforcing fibers and contains the component fibers in such a manner that the mixing ratio thereof varies in the direction of thickness of the material.
2. Prior Art Statement
Various methods for the production of a fiber-reinforced composite article have heretofore been proposed and put into practical use. The present inventors also have proposed methods for producing such a fiber-reinforcing composite article by mixing reinforcing fibers with a powdery or granular thermoplastic resin and thermally molding the resultant mixture (Japanese Patent Publication No. 33148/1976 and Japanese Unexamined Patent Public Disclosure No. 303626/1992).
These methods share a procedure of uniformly mixing a matrix material with reinforcing fibers and molding the resultant mixture but do not specify the distribution of the mixing ratio of the components in the direction of thickness of the composite article. To date, various kinds of fiber-reinforced composite articles have found utility in numerous applications. In particular, there has been increasing demand for the fiber-reinforced composite articles in which the ratio of the components varies in the direction of thickness. This invention pertains to a method for the production of a material for a composite article which responds to this demand.